Electrical radiant heating systems have become increasingly popular because of the high efficiency of the utilization of the electrical energy. One of the most effective forms of this system is the incorporation of a grid of electrical resistance-conductors in the floor structure of a room so that the entire floor becomes a radiant heating panel. The maintenance of this large surface at a temperature very slightly in excess of the personal comfort level will provide uniform heat with a minimum loss of heat to the surrounding structure from conduction and convection. Heating a room by warming the air tends to produce a stratification of the air in which much of the heat accumulates near the ceiling. The result is a relatively cold floor, and a substantial heat loss through the ceiling structure, in addition to the necessity of maintaining a somewhat higher air temperature than is necessary for personal comfort. The apparent room temperature is considerably less than the maximum at the upper levels of the room.
The low temperature requirements of the electrical resistance system associated with a radiant floor permits the use of common insulating materials, and eliminates the fire hazard that would be associated with glowing resistor elements commonly associated with electric hot-air systems.
The apparent simplicity of a floor installation of resistor elements is, however, somewhat deceptive. Experience with this type of system has established that continuous sealed insulation must be maintained between the various portions of the resistor system in order to prevent short circuits from the presence of moisture, or from contact with foreign materials or conductive structural members. This is particularly the case when an attempt is made to incorporate the grid system in concrete floor construction. The arrangement shown in my previous U.S. Pat. No. 3,223,825, issued on Dec. 14, 1965, had many desirable functional characteristics, but experience with this system disclosed the need for a number of improvements. The present system provides these improvements, and establishes an integrated system that can be installed through routine procedures by workmen of ordinary skill, with the performance being predictable and relatively maintenance-free.